I purchased three of these
MAGLITE 2-D cell LED flashlights last fall and have been impressed with them.
They are much brighter than the conventional bulb version they replace, yet you can get about 30 hours of usable light from a set of batteries. The advantage of D cells is that they have about 7 times the energy of AA cells, yet cost little more. I also have many smaller LED flashlights that run on just a single AA cell and these are great when you don't want the size and weight of a D cell flashlight.